remove unused files and remove unnecessary elements in index.html

Author: martinhaintz

flutter/example/lib/main_test.dart

@@ -39,17 +39,6 @@
     <div id="left" style="width: 50%; height: 100%; float: left;"></div>
     <div id="right" style="width: 50%; height: 100%; float: left;"></div>
   </div>
-  <!-- This script installs service_worker.js to provide PWA functionality to
-       application. For more information, see:
-       https://developers.google.com/web/fundamentals/primers/service-workers -->
-  <script>
-    if ('serviceWorker' in navigator) {
-      window.addEventListener('load', function () {
-        navigator.serviceWorker.register('flutter_service_worker.js');
-      });
-    }
-  </script>
-  <script src="main.dart.js" type="application/javascript"></script>
   <script src="flutter_bootstrap.js" type="application/javascript" async></script>
 </body>